Added the "ArgumentParser" package dependency to the sample target in the Package file.

Package.swift

@@ -18,6 +18,7 @@ let package = Package(
         ),
     ],
     dependencies: [
+        .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.4.0"),
         .package(url: "https://github.com/hummingbird-project/hummingbird.git", from: "2.0.0"),
         .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.1.0"),
     ],
@@ -33,9 +34,16 @@ let package = Package(
         .target(
             name: DocCMiddleware.sample,
             dependencies: [
-                .byName(name: DocCMiddleware.target)
+                .byName(name: DocCMiddleware.target),
+                .product(name: "ArgumentParser", package: "swift-argument-parser"),
             ],
-            path: "Samples/DocCMiddleware"
+            path: "Samples/DocCMiddleware",
+            swiftSettings: [
+                // Enable better optimizations when building in Release configuration. Despite the use of
+                // the `.unsafeFlags` construct required by SwiftPM, this flag is recommended for Release
+                // builds. See <https://github.com/swift-server/guides#building-for-production> for details.
+                .unsafeFlags(["-cross-module-optimization"], .when(configuration: .release)),
+            ]
         ),
         .testTarget(
             name: DocCMiddleware.test,